Hands-free (speakerphone) telephone stations are widely used in conference calls. Disadvantageously, if such telephone stations do not employ sophisticated noise cancellation techniques, then the background noise that is "picked up" at a hands-free station that is being used to monitor a conference call will, nevertheless, be transmitted to the other participants (conferees). Such background noise could be very annoying to the other participants. For this and other reasons, a hands-free telephone station is typically equipped with a so-called muting button that "mutes" all voice (including background noise) transmissions whenever the muting button is operated. Thus, a conferee who has operated the muting button on his/her hand-free station set may listen to the other participants in a conference call without being heard by them. (It is apparent that the foregoing also applies to a conventional wireless (cellular) station set.)
The values of respective voice/signal samples generated by a cellular/wireless station set are set to zero whenever a user of a hands-free wireless station operates the muting button during a telephone call. The setting of the voice signals to zero signifies the absence of a voice, which means that voice messages from the wireless mobile station set to a base station ceases during the time that the mute feature/function is set.
As is well-known, the wireless link over which voice messages are transmitted from a wireless station to a base station is very susceptible to (a) distortion due to shadowing, (b) fading effects due to multipath transmission, (c) the motion of wireless station, and (c) channel noise. The messages that are received at a base station via a noisy channel will then most likely contain an appreciable number of errors, many of which are not correctable. Consequently, such errors distort the signals that the base station outputs for that channel, and such signals are transmitted to a receiver as intrusive noise. In fact, the level of such noise could become very annoying to the listener. If the wireless station is participating in a conference connection, then it is likely that because of such noise, the other conferees may insist that the wireless participant disconnect from the conference connection.